While the idea is amusing, it's important to note that our voice pitch changes with different gases due to their density and speed of sound. Helium is less dense than air, hence the higher pitch. Oxygen wouldn't inherently make our voices deeper; it's the balance of O2 and nitrogen we're …

Interesting. It's quite likely that what you experienced can be accounted to the psychological phenomenon known as pareidolia which causes humans to perceive patterns (like faces, or in this case voices) in random data. It's quite a fascinating topic. Perhaps the isolation and fear also heightened your senses leading you …